Wound healing is a basic reparative process. It has been known throughout time that dressing wounds with appropriate materials aids the natural regenerative process. Historically, such materials have been made from cotton fibers such as gauze. These dressings are beneficial to the healing process because they insulate damaged tissue from external contaminants and because they remove potentially deleterious wound exudates.
As science and medicine have advanced, the technology incorporated into wound healing devices has improved substantially. Highly absorbent wound contact devices capable of absorbing many times their weight in liquids are available. Systems that temporarily seal wounds and utilize suction to remove exudates have found widespread utilization. Devices incorporating anti-microbial agents and biologic healing agents are common. Devices that provide a moist wound environment for improved healing have been found to be useful.
Nevertheless, many common conventional and state-of-the-art wound contact devices have shortcomings, particular for use in suction wound therapy. In an example, gauze and other similar flat fabric materials are commonly used in wound dressings. When gauze in contact with a wound becomes wet with wound exudates, it becomes soggy and soft, losing any structure it may have had and leaving little or no space above the wound surface for new tissue growth to occur. When suction is applied to a gauze wound dressing, the dressing is compressed into a flattened state and any space between the gauze fibers is effectively eliminated. Additionally, even when wound exudates are being removed by suction from a gauze dressing, the gauze remains saturated and pressed against the wound, leaving no space above the wound and thus inhibiting new tissue growth.
In another example, a dressing using a foam material in contact with the wound retains only a minimal amount of small pores at the wound contact surface when suction is applied to the dressing. When a foam dressing is used with suction, the pores of the foam collapse, eliminating space above the wound surface. Absent significant open space above the wound surface, new tissue grows into the foam. Routine removal of the foam dressing causes disruption of new tissue, excessive bleeding, and unnecessary discomfort to the patient. In-growth of tissue into foam is a significant problem because the tissue has nowhere to grow but into the collapsed cell or pore structure of the foam.
In another example, a dressing using a wound contact device in the form of a relatively rigid perforated sheet, such as an Aquaplast sheet, as a substrate in contact with the wound, is not sufficiently flexible and conformable to comfortably and adequately conform to wound surfaces that are often irregular in contour. A dressing having such an inflexible or rigid structured material or wound contact layer causes unnecessary pain and discomfort in a patient. In addition, an Aquaplast or similar sheet is constructed from solid plastic with large holes punched into the plastic. Such a sheet does not have small interconnecting interstices that facilitate the transport of liquid wound exudates away from the surface of the wound. The holes in the Aquaplast sheet simply create reservoirs where deleterious wound exudates can pool and impede wound healing. Because these large holes do not fluidically communicate with each other, fluid removal is not practical. In addition, an Aquaplast sheet does not provide any wicking for the effective removal of wound exudates. Further, an Aquaplast sheet is not permeable to either gas or liquids, and thus does not permit a wound to breath in the places where the sheet material is in contact with the wound surface, nor does it enable efficient transport of fluids and wound exudates away from the wound.
A wound dressing for use in suction wound therapy preferably has some or all of the following characteristics and properties: the dressing should be flexible and conformable to the wound, the dressing should effectively enable transport of wound exudates away from the wound surface, and the dressing should allow sufficient voids above the wound when suction is applied for unobstructed new tissue growth. The dressing should maintain structural integrity when moist and should have a geometry to actively encourage tissue growth. When used in the later stages of tissue regeneration, the dressing should inhibit or minimize entanglement of healthy new tissue into the dressing material. Early in the treatment of some wounds, there may be necrotic or dead tissue in the wound. This dead tissue can be a source of nourishment for deleterious bacteria. A dressing for treating such wounds may have a wound contact surface adapted to debride or remove dead tissue out of the wound.
As described in U.S. patent application Ser. No. 10/982,346, commonly assigned with this application and from which this application is a continuation in part, wound dressings and wound contact devices have been developed to replace traditional gauze or foam pads under wound bandages or wound sealing covers used in suction assisted wound healing. The goal has been to enhance the healing process though the properties and geometries of wound contact devices.
One such wound contact device comprises a permeable material having a plurality of dimple voids formed in the wound contact side of the device, wherein the dimple voids are preferably disposed in a randomly spaced pattern. Because the contact device comprises a permeable material with interconnecting interstices, it can effectively transport deleterious wound exudates away from the wound surface. The device can be cut to size for a wound, and the cut piece placed in contact with the tissue of the wound under a bandage or under a sealing cover. The dimple voids provide empty space into which new tissue can grow without becoming excessively intertwined with the permeable material, in contrast to the intertwining growth that is known to occur with porous foam pads. The contact elements between the dimple voids provide a main tissue contact surface. The permeable material of the contact device provides sufficient resistance to compression to keep the dimple voids from entirely collapsing when suction or other compacting pressure is applied to the wound dressing. Additionally, the contact device maintains the dimple voids in the presence of moisture.
In addition to providing empty growth space, the combination of the dimple voids and the contact elements imposes a beneficial strain on the tissue when suction is applied to the wound dressing, pulling the tissue into a catenary-like shape within the voids. These forces and the resulting strain imposed on the tissue are believed to stimulate new tissue growth more effectively than the forces obtained in suction therapy using wound dressings that have generally flat surfaces when suction is applied.
It would be advantageous to provide an improved wound contact device comprising a permeable structured material and a wound contact layer affixed to a side of the structured material forming a wound contact surface, with a plurality of voids extending through the contact layer to a depth within the structured material and defining wound contact elements on the wound contact surface. In one embodiment, it would be advantageous to provide a wound contact device having a wound contact surface adapted to prevent healthy tissue growth from becoming entangled with the device. In another example, it would be advantageous to provide a wound contact device having a wound contact surface adapted to debride dead tissue out of a wound so that revascularized healthy tissue can grow. The nature of these improvements and the benefits they confer will be apparent from the description and sample embodiments which appear below.